The prior art has proposed the feeding of particulated metal oxides such as iron and nickel ores, possibly partially reduced by a pretreatment, to a coke bed heated to incandescence, meaning a temperature high enough for the coke to react with the oxygen of the oxides and produce molten metal. Also, it has been suggested that the coke bed be electrically heated.
However, there has been no way to electrically heat the coke bed efficiently enough to make the above concept commercially practical. It is, of course, possible to use an electrically non-conductive hearth for carrying the coke bed, but the melt formed by the reduction of the oxides is of high electrical conductivity, the coke bed of substantially lower electrical conductivity, floating on top of the melt. Consequently, any attempt to pass current through the coke bed by any means, inductively or directly, means that the current must be largely shunted through the melt, the coke bed being heated only by conduction from the melt. The maintenance of the coke bed and the feeding of the oxides to this bed, present serious problems.
The object of the present invention is to heat the coke bed electrically by passing a current through the coke bed, without the current being shunted by the molten metal produced from the oxides, while providing for the maintenance of the coke bed and the feeding of the oxides to it in a practicable manner.